Myocardial perivascular fibrosis and media:lumen ratio in control and diabetic rats. Perivascular collagen ratio (C) was assessed via picrosirius red staining in control (A) and diabetic (B) rats (20× objective). Vessel media-to-lumen ratio (F) was assessed via haematoxylin and eosin staining in control (D) and diabetic (E) rats (20× objective). There was no significant difference between groups. Control, n = 6 and diabetic, n = 8. Values expressed as mean ± SEM.